In a standard knotter of the Cormick type the two ends of the loop of wire or twine, hereinafter referred to as the strand, are tied together by a knotter comprised basically of a strand holder which secures and eventually cuts the strand free from its supply and a knotting head having two vertically spaced holding and clamping jaws rotatable about a vertical axis. The knotting head lies between the holder/cutter and the bale or other item being trussed. Normally the knotting head makes a single revolution, with its jaws open at the start to capture the two strands and then closed so that the loop then formed around the jaws can be pulled over the ends in the jaws. The upper jaw has a hook which catches the two strands so that as the bale is pushed out of the compaction chamber of the baler the loop is pulled off the head to form a simple double overhand knot. This action leaves the longer of the two strands hooked in the upper jaw and formed into a loop engaged in the knot which is then pulled off the head.
In the Deering system the two strands are engaged in the same edge opening of the holder. When same is turned the opening is closed by a cam and both strands are gripped. Once again during the knotting operation the knotting head makes a single revolution about its axis, first gripping both strands and forming a loop about itself with the two strands engaging under the hook of the head. Then the jaws close. A knot puller draws the loops thus formed off the jaws and is provided with a device for cutting the strands on the far side of tee knot, that is the side away from the object being tied up.
In this arrangement after the head turns the knot puller swings toward the points of the knotting head. First then the strands are cut so as to leave two short ends of the same length. On further movement of the knot puller this knot puller draws on both strands leading from the jaws of the knotting head to the bale so that the two loops around the jaws are pulled off over the strands gripped between the upper and lower jaws and the strands are pulled straight out of the knotting head. This forms the knot and pulls it from the knotting head.
Both these systems have the disadvantage that they kink the strands considerably, that is bend them through very tight radii. As a result the knot itself will have a strength equal to at most 50% to 60% of the strength of the strand. Accordingly it is necessary to use a wire or twine whose tensile strength is substantially greater than that actually called for by the task in order to compensate for the weakness at each knot.